The Effect of Household-based Screening on Blood Pressure Changes in South Africa

NCT03762304 | Completed

• 1 other identifier: RDD - BP - South Africa
• Study Type: observational
• Target: 3,986
• Locations: 0 countries
• Sites: N/A

Brief Summary

This study will evaluate the effect of household-based screening and care encouragement for blood pressure on subsequent changes in blood pressure. The study uses a quasi-experimental regression discontinuity design with existing population-based secondary data from the 2008, 2010, 2012, 2014, and 2017 waves of the National Income Dynamics Study in South Africa.

Conditions

Hypertension; Blood Pressure

Keywords

Causal inference; Regression discontinuity

Outcome Measures

Primary Outcomes (2)

• Two-year change in systolic blood pressure

  For each survey wave, blood pressure is measured at the household by a trained enumerator using an electronic blood pressure device. The enumerators take two separate measurements during the course of the visit with at least three minutes between measurements with individuals in a seated position. The investigators will take the average of the two systolic blood pressure measurements as their main outcome measure.

  Approximately two years based on the difference between survey waves in the years 2008, 2010, 2012, 2014, and 2017

• Nine-year change in systolic blood pressure

  For each survey wave, blood pressure is measured at the household by a trained enumerator using an electronic blood pressure device. The enumerators take two separate measurements during the course of the visit with at least three minutes between measurements with individuals in a seated position. The investigators will take the average of the two systolic blood pressure measurements as their main outcome measure.

  Baseline in 2008 and approximately nine years later in 2017.

Secondary Outcomes (2)

• Health-seeking behavior

  Cross-sectionally in 2010, 2012, 2014, and 2018

• Blood pressure treatment

  Cross-sectionally in 2010, 2012, 2014, and 2018

Study Arms (2)

Intervention group

The intervention group consists of individuals with a measured blood pressure just above the hypertensive cut-off of 140 mmHg systolic or 90 mmHg diastolic blood pressure who have never previously been diagnosed as hypertensive and are not taking medication to lower their blood pressure. The exact upper bound on blood pressure will be determined empirically. Individuals in the intervention group were told that that their blood pressure was high, that high blood pressure can lead to life threatening consequences, that blood pressure control can reduce these negative consequences, and that they should seek follow-up care for their blood pressure.

Other: Household blood pressure screening with care encouragement

Control group

The control group consists of individuals with a measured blood pressure just below the hypertensive cut-off of 140 mmHg systolic and 90 mmHg diastolic blood pressure who have never previously been diagnosed as hypertensive and are not taking medication to lower their blood pressure. The exact lower bound on blood pressure will be determined empirically. These individuals were not given the care encouragement intervention.

Interventions

Household blood pressure screening with care encouragement OTHER

During the household survey visit, survey enumerators collected two measurements of the respondent's blood pressure. If either of the measurements exceeded 140 mmHg systolic or 90 mmHg diastolic, enumerators told participants: "Your blood pressure readings are higher than normal. High blood pressure is dangerous because it makes the heart work too hard. High blood pressure increases the risk of heart disease and stroke. High blood pressure can also cause other problems, such as heart failure, kidney disease, and blindness. You can control high blood pressure by taking action." Then the enumerators recommend that an individual seek medical care within 2 months.

Intervention group

Eligibility Criteria

• Age: 30 Years+
• Sex: all
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Probability Sample

Study Population

Individuals will be drawn from the 2008, 2010, 2012, and 2014 waves of the National Income Dynamics Study (NIDS) with the 2017 wave used only for follow-up. The NIDS is a nationally representative, household-based, survey of families and individuals from across South Africa.

You may qualify if:

• Age greater than or equal to 30
• Valid blood pressure measurements

You may not qualify if:

• Prior diagnosis of hypertension
• Currently taking medication for blood pressure
• Measured with a blood pressure above 140 mmHg systolic or 90 mmHg diastolic in a previous wave of data

Sponsors & Collaborators

• Till Bärnighausen: lead
• Emory University: collaborator

MeSH Terms

Conditions

Hypertension

Condition Hierarchy (Ancestors)

Vascular Diseases; Cardiovascular Diseases

Study Officials

• Nikkil Sudharsanan, PhD

  Research group leader

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Alexander von Humboldt University Professor

Study Record Dates

• First Submitted: November 30, 2018
• First Posted: December 3, 2018
• Study Start: February 1, 2008
• Primary Completion: December 1, 2017
• Study Completion: December 1, 2017
• Last Updated: December 7, 2018

Record last verified: 2018-12

Data Sharing

• IPD Sharing: Will share
• Time Frame: Data are already available.